1. Field of the Invention
The present invention relates to an information device provided with a touch-sensitive panel and a computer-readable storage medium for computer program executed in such an information device. An example of the information device is a Multi-functional peripheral (MFP) having a print function and various information processing functions.
2. Description of the Related Art
Touch-sensitive panels are widely used as means through which manipulations are performed on information devices. A touch-sensitive panel herein is an input/output device in which a display capable of displaying screens and a touch-sensitive pointing device are combined with each other. The pointing device transparent to light is brought into intimate contact with the front face of the display. The surface of the touch-sensitive panel functions as both a screen and a touch input screen. In the touch-sensitive panel, what is displayed on the screen changes appropriately in accordance with manipulations by a user.
Concerning manipulations on an information device via a touch-sensitive panel, a Graphical User Interface (GUI) is known. According to the GUI, an operating screen (image for operation) having a size larger than that of a display is scrolled so that the whole image can be viewed. There is proposed a digital multifunctional device having an operational display panel (Japanese Laid-open Patent Publication No. 2005-244360). In the operational display panel, slider bars extending in the horizontal and vertical directions respectively are provided outside a display of a touch-sensitive panel. When a part of an address list for facsimile or data transmission is displayed on the display, a user of the digital multifunctional device moves sliders in the slider bars to scroll up, down, or across the address list. The positions of the sliders in the slider bars indicate a relative position of the displayed part of the entire address list.
Meanwhile, recent mobile information devices such as a tablet personal computer or smartphone are configured to receive, as scrolling, “drag” gestures and “flick” gestures by one finger or pen. The “drag” gesture means touching a spot, with the finger or pen, on a touch input screen to drag the finger or pen thereon. The “flick” gesture means touching a spot, with the finger or pen, on the touch input screen to move the finger or the pen in a quick flicking motion. In the drag gesture, the screen is generally scrolled at a speed substantially the same as that of the movement of the finger or pen, and the screen is generally scrolled by a distance substantially the same as that of the movement of the finger or pen. In the flick gesture, the screen is generally scrolled by a distance longer than a distance the finger or pen moves on the touch input screen, and the screen is generally scrolled in a larger degree as the finger or pen moves quicker on the touch input screen.
As for the drag gesture, there is proposed a technology for changing a color and a size of a draggable icon depending on manipulations. According to a display disclosed in Japanese Laid-open Patent Publication No. 2004-070492, when a user touches a draggable icon on a screen with his/her fingertip, a color of the icon is changed to notify the user that the icon is draggable. Then, when the user performs operation for pushing the icon, the display changes the size and color of the icon to notify the user that the icon is ready to be dragged.
The flick gesture and the drag gesture are useful to scroll a display made on the screen. The entirety of the scroll screen functions as a button for scrolling. This eliminates the need for the user to look for a button designed specifically for scrolling. This also enables the user to freely scroll a display on the screen in one direction or a direction opposite thereto while watching the screen.
The user sometimes repeats a quick flick gesture in one direction in order to scroll the screen little by little. The user sometimes alternates between scrolling in one direction and scrolling in the opposite direction. Here is an example of displaying an address book indicating addressees and telephone numbers corresponding thereto. In such a case, in spite of the fact that the addressees and the telephone numbers are listed in sorted order by addresses (for example, in alphabetical order by the first letter of the addressee), the user sometimes scrolls through the address book repeatedly. A reason why such operation is repeatedly performed is as follows: When the user scrolls the screen one time and the screen stops being scrolled, he/she subsequently scrolls the screen again without being aware of which part of the entire image the displayed non-scrolled image corresponds to.